


voyeuristic tendencies

by orphan_account



Category: Undertale (Video Game)
Genre: Accidental Voyeurism, Body Worship, Guilt, M/M, no glowy magic dicks in this one sorry, sorta - Freeform
Language: English
Status: Completed
Published: 2016-01-02
Updated: 2016-01-07
Packaged: 2018-05-11 01:31:45
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 3,810
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/5608675
Author URL: https://archiveofourown.org/users/orphan_account/pseuds/orphan_account
Summary: <blockquote class="userstuff">
              <p>"He didn’t mean to see. It was an accident, a complete coincidence. It wasn’t his fault. He didn’t mean to."</p><p>papyrus learns why it's important to knock</p>
            </blockquote>





	1. Chapter 1

**Author's Note:**

> w e l p here we are with more sin
> 
> guilty voyeur pap is my shit tbh

 

 

He didn’t mean to see.

It was an _accident,_ a complete coincidence. It wasn’t his fault. He didn’t _mean_ to.

He’d come home from late night training at Undyne’s- a regular Tuesday occurrence- hungry and comfortably sore, when he’d heard it. A small muffled sound from up the stairs. sans’ room.

Maybe he was having another one of those bad dreams he’d been having more and more lately, Papyrus thought, putting down the pot of water he’d just filled up. He paused, listening in silence for a few moments. Just when he was beginning to wonder if he’d imagined it, opening the cabinet and reaching for one of the many boxes of spaghetti noodles, he heard it again. A faint sort of gasp this time. Definitely sans.

Papyrus shut the cabinet quickly and hurried up the stairs. He didn’t bother knocking- sans never heard him during these dreams, never seemed to hear anything other than whatever was going on inside his head- and cracked the door open softly.

“sans?” he asked softly, “Are y-“ his words died halfway out of his mouth at the sight that met his eyes.

sans was not having a bad dream. He wasn’t even sleeping, surprisingly. He was lying down, yes, but definitely not sleeping.

His brother was spread out on his bed, sheets pooling around his waist, with one hand grasping at his pillow and the other… underneath the sheets, movement right about where his pelvis would be, face flushed and panting. The muffled gasp was not the result of some mysterious night terror, Papyrus realized _very_ clearly as another soft little groan fell from his open mouth. He felt his face burn at the sound.

He didn’t seem to realize Papyrus was there, didn’t seem to have heard him at all, which Papyrus was suddenly _very_ grateful for. He didn’t know what he would do if sans were to look at him right now, it would be embarrassing and awkward for both of them and he knew if sans turned his head at all he would _see_ him watching and he knew he had to shut the door right now and run back downstairs and keep making dinner and pretend this never happened.

But he… couldn’t seem to look away. Nothing but the sound of the sheets shifting with the movement of sans’ hand and his slow, heavy panting filled the room. Papyrus couldn’t _see_ anything, not really, but he knew, vaguely, what was going on under that blue. sans’ hand was slow and practiced, and Papyrus wondered faintly how often he did this, if it was every Tuesday when he went out or if this was the reason he spent so much time in his room— he must’ve only done it when Papyrus wasn’t home, because he’d never heard any strange sounds like this before, and why did he feel a warmth gathering in his crotch and why were his cheeks burning when he wasn’t the one doing such lewd things and—

A sudden sharp moan shook him from his daze, and Papyrus shut the door as quickly and quietly as he could before rushing down the hallway to his own bedroom.

Dinner could wait. He wasn’t very hungry anymore anyways.

His face was still burning— he’d _never_ seen or heard anything like that before, and he’d never seen his brother so… uncollected, other than the nightmare nights when he had to calm him down.

He heard another sound from the room next door and felt his flush deepen. There was that weird feeling between his legs again- it felt odd and tingly and uncomfortable. He sank to the floor and pressed his legs together and tried to block out the sounds and the images playing through his mind again until it went away.

He could barely look his brother in the eye for the rest of the night.

 

The next time, maybe he sort of meant to see. Kind of. It was still a bit of a coincidence though. Really.

It wasn’t even a Tuesday, so how was he supposed to know it was going to happen again? He didn’t know it was going to happen again, and he didn’t know for sure that it wasn’t a nightmare. sans slept sporadically, so what if he was trapped in a terrifying dream so terrifying he cried out in terror? What kind of brother would Papyrus be if he didn’t check and make sure sans was okay?

So he didn’t really mean to see. It was like the first time— he thought his brother needed help, that was all. It wasn’t his fault he was wrong.

It was kind of his fault that he didn’t shut the door right away again when he found out.

He didn’t know _why_ he didn’t shut the door.

He was just curious, he reasoned. He didn’t really know about this sort of thing very much and sans obviously knew a lot and he just wanted to know what was going on.

This time, sans wasn’t under the sheets. He was sitting up this time too, leaning back on one hand with the other one buried in his shorts. Those slow movements. Soft gasps and twitches.

This time, sans leaned forward a bit, balancing out his weight and trailing his other hand up and under his shirt, his jacket hanging off his shoulders. He let out a low, slow breath as he grasped what Papyrus guessed to be his spine.

The weird tingly warmth was back, he realized with a start, flooding into his bones at an alarming speed.

sans curled forward on the bed, sucking in a shaky breath. Papyrus took this as his cue to leave, shutting the door and hurrying down the hallway again. He sank to the floor again, his back to the door, feeling oddly breathless for some reason.

The feeling was still there, stronger than before, vaguely pulsing. That was alarming.

He didn’t know what to do about it. It had eventually gone away last time, but it took a while and left him feeling oddly unsatisfied. He glanced down at himself. Whatever sans had been doing to himself had obviously felt pretty good. Maybe he should…

He blushed. Pulling his gloves off, he slowly trailed a hand down to rest on the center of his clothed pelvis. Nothing, at first. He tried adding a bit of pressure, pushing down slightly and rubbing and _oh._ That felt… that felt nice.

Really nice.

He slipped his hand under the cloth, bone making contact with bone and _wow_ , that felt _really_ nice. How had sans done it? Slowly?

He tried to copy the movements he’d seen, the stroking and jerking, but it was hard to copy what you hadn’t _seen_ seen. Eventually, he fell into a sort of rhythm, body on autopilot. He pictured sans’ hand moving under his shorts and grasping at his sheets and felt pressure build up, bigger and bigger and— he stopped, scared. Was it supposed to feel like that? He didn’t know what would happen if he kept going, he felt like he was going to explode. Had he done something wrong?

It took even longer for the feeling to go away that time.

 

The third time, he did mean to see it. A lot. No coincidence about it really.

It was still just curiosity though, he told himself. He didn’t know what happened at the end, didn’t know what the pressure would do if he kept going. He just wanted to find out how it ended.

It was a Tuesday again. He’d told Undyne that sans was feeling ill, so he had to go home early. He didn’t think she really believed him, but she told him to tell sans she hoped he felt better soon and let him go without argument.

When he peered through his brother’s door for the third time, Papyrus thought he knew what he was expecting. He did not expect his brother’s shorts to be bunched around his knees, shirt hiked halfway up his ribcage. It was like every time he watched, his brother was more and more exposed. Every time he watched, he was invading his brother’s privacy further and further— he pushed the thought from his mind. This was the last time. He just wanted to know what would happen.

He’d _never_ seen his brother like this before. Bony fingers curling around his ribs, his pelvis, dragging along his tailbone, stroking and rubbing. Hips moving, rolling up to meet his hand every so often. He threw his head back, eyes fluttering shut, eyebrows drawn up in bliss. And the sounds— low moans and quivering gasps and curses when he found a particularly sensitive spot.

Papyrus had to put a hand over his mouth to keep himself from making any noise.

His brother looked… amazing. All spread out and flushed an adorable dark blue, and he wondered vaguely if anyone else had ever seen him like this, or if Papyrus was the only one. He hoped he was. He hoped he was the only one who had ever seen his brother like this.

The feeling came quickly this time, and it grew and grew as he watched, enthralled.

It didn’t take too long for his brother to reach his peak, the pressure Papyrus was so worried about. sans moaned, a drawn out, broken, trembling moan, back arching, clutching at the sheets on his bed, and then collapsed back onto the mattress, panting, something blue and sticky coating his hand.

Papyrus shut the door slowly this time, and when he reached his own peak back in his room, it was to the sound of sans’ moan ringing in his ears.

 

He stayed away for a while after that.

He heard the tell tale sounds and walked in the opposite direction. When his own hand slipped under his clothes, he tried not to think about the way sans’ back arched off the bed or way he gasped when he gripped his spine or what it would feel like if it were his brother’s hand on his pelvis instead of his own. If it were his hand on sans’ pelvis.

What sort of noises he would make if he grasped his ribs or kissed his spine or ran his hands up his thighbones. What his name would sound like on his lips. He wondered if it was possible for skeletons to kiss. A part of him wanted to find out. Another part of him wanted to lock the other part of him in a closet because this was sans they wee talking about, this was his _brother_ , and he never should’ve opened the door on that damn Tuedsay night.

And he tried, he tried really really hard to stay in his room or keep cooking or pay attention to the television show, but one night found him with his back to his brother’s bedroom door, fighting the urge to peek inside.

And when he did finally choose, his hand found its way down, moving in time to his brother’s.

God, he was so screwed.

 

 


	2. Chapter 2

**Summary for the Chapter:**

> He wasn’t sure if anything could make him look away right now, not when sans was so close, nothing but—
> 
> His phone rang. 
> 
> He didn’t remember vibrate mode being this _loud._

**Notes for the Chapter:**

> wasn't rlly planning on a second chapter but i got a few ppl asking about sans' reaction and i couldn't help myself
> 
> also it got kinda out of hand
> 
> this is so self-indulgent tbh

 

Papyrus had made a few mistakes in his life. After all, how could someone truly become great without improving as a person? One had to make a mistake before they could fix it.

So he could admit that yes, he’d made a few mistakes.

Though this particular mistake- this was a mistake he could never admit to. Not a mistake, really. More of a bad bad habit he never meant to develop.

It was a Friday, this time.

He trained early in the morning on Fridays, coming back a few hours before noon. He’d showered, dressed, and was ready to make an early lunch when he made his next mistake in what had become a long series of mistakes.

He evidently hadn’t been very loud about his return home. Usually when he was, nothing would happen. Nothing ever happened when he was home, or awake, sans made (or tried his best to make) sure of it. But Papyrus hadn’t been loud enough and sans thought he was still gone and dammit dammit he was going to have to postpone that midday spaghetti because of his horrible bad habit.

He could just walk away. He should just walk away. He didn’t really want to walk away.

He didn’t walk away. He walked towards. Tiptoed down the hall and cracked open the door and braced himself.

He was right. There was sans: oblivious to his audience, lying out on his bed with one hand over his mouth and the other stroking in slow movements down his shorts. All lovely muffled sounds and raw emotions he rarely saw these days.

God, he was horrible. But, as usual, he couldn’t look away. He wasn’t sure if anything could make him look away right now, not when sans was so close, nothing but—

His phone rang.

He didn’t remember vibrate mode being this _loud_ , and he jumped at least a foot in the air as he struggled to turn it off. Shit. Shit shit.

Inside the bedroom, he saw sans jump at nearly the same time, eyes snapping open.

Slowly, very slowly, he turned his head, and made direct eye contact with Papyrus, who was clutching his phone and frozen in place.

There was silence. One moment. Two. Then:

“o-oh my _god_ what the _hell_ , papyrus!” sans snapped into action, yanking his hand out of his pants and pulling the sheets over himself, blushing furiously, “haven’t you ever heard of knocking??”

“I- um-“ he stuttered, searching frantically for something to say, “I heard a strange sound and… and I thought that maybe you were having a nightmare.” and it wasn’t a _lie,_ really- it was the reason this whole horrible habit had started.

At that, some of the embarrassed anger dropped from his expression, but he still looked mortified.

“How much did you see?” he asked quietly.

“N-nothing, really,” he lied, “My phone rang right when I opened the door— I’m sorry, brother.”

sans sighed heavily, cheeks still flaring blue, “it’s fine, pap, just… knock next time, okay?”

Papyrus gulped, looking down at where sans’ hands were holding the sheets close against his body. He wondered if… maybe…

“Do you, um,” he started, scratching the back of his neck before standing up taller to seem more sure of himself, “Do you want a hand with that?”

\--

Now, sans had been in some pretty uncomfortable and/or embarrassing situations before— that time Papyrus had heard him singing in the shower when he thought no one was home, that time he had completely messed up a presentation in front of half the school when he was little, that time he’d gotten a little too drunk at Grillby’s— but he always knew how to talk his way out of them. He always knew how to deal with them.

But this- glancing over with his _hand down his shorts_ to see his _little brother_ just _staring_ at him with _something_ in his expression that sans couldn’t quite place, and then asking him _that_ \- this was something he didn’t know how to deal with.

“w… _what?_ ” was all he managed to say.

Papyrus shifted, looking more unsure than sans had maybe ever seen him, glancing away and swallowing before glancing back.

“Well I mean… I’m here, and you haven’t… _finished_ yet,” he said the word slowly, like he was testing it out, “and I know how uncomfortable it is to stop right in the middle.”

sans’ mind was blank. He… what? Papyrus knew _what?_

_Papyrus_ knew??

“what?” he asked again- it seemed to be the extent of his vocabulary at the moment.

Papyrus’ face fell, “Unless, you want me to leave?”

The disappointment in his voice snapped sans out of his daze enough to speak again.

“It’s just…” he hesitated, “we can’t. We’re- y’know- we’re _brothers,_ pap, we’re bros.” which was why this was all so bizarre, he thought.

Paps’ face fell even more, and he looked slightly ashamed at the reminder, “I _know,_ but I just-“ he looked away again, voice dropping “I just really want to. I want to make you feel good, sans.”

sans blinked.

Oh.

He felt his face flush again.

And yeah, he probably could’ve talked his way out of this now, could’ve maneuvered Papyrus out of his room and pretended this never happened- he was good at avoiding things, and okay at saying no. But hell if he’d ever been able to say no to his little brother before- especially not when he looked so sad and nervous and disappointed because of him.

Fucking hell.

“um. if,” sans cleared his throat nervously; Pap looked back up at him, “if you want to.”

“What?” a little hopeful surprise in his voice.

“i-if you really want to, then… sure.”

“…Really?” he sounded like he was trying not to sound too excited.

“yeah.”

Papyrus blinked, like he was trying to figure out if he was lying.

“You’re really sure?” he asked.

sans hesitated again, before he nodded, “i’m sure. can’t say no to the great papyrus, right?”

Papyrus’ face lit up as he approached the bed. sans scooted back a bit to make room for his brother, who climbed on and softly pushed sans back down onto the bed. sans felt extremely vulnerable for a moment- he’d never done this before- before he reminded himself that this was Papyrus, that he had no reason to be worried.

The taller skeleton paused for a moment, as if unsure how to start, before he nodded decisively to himself. He smiled reassuringly at the boy underneath him. Then he tugged his gloves off and placed a boney hand on his knee.

sans swallowed. His nonexistent throat felt vaguely dry.

“i’ve, um,” he gave a nervous grin, “i’ve never actually, uh, done this before.” (And was it just him or did Papyrus look almost _pleased_ at the statement).

“Don’t worry,” he said, “Neither have I.”

And then he slid his hand up his thighbone.

sans jolted in surprise, legs parting automatically at the touch. Papyrus took the opportunity to shuffle in between them, hand sliding up further to rest on his waist. Here, he paused, eyes roaming up and down.

The smaller skeleton looked away self-consciously. Normally he didn’t give a flying fuck about what he looked like, but here was one of the few people who’s genuine opinion he cared about, gazing at him he was something important.

“You look very nice like this, sans,” he remarked quietly, almost shyly, and Papyrus was many things, but he was hardly ever shy.

sans’ face flushed at the praise.

“jeez, pap, i— ah!” he gasped as his ribcage suddenly made contact with the air, shirt hiked up to his collarbone, a sharp contrast to the heat he was feeling.

Then there were hands trailing lightly down his ribs, rubbing over each one with a careful precision that had him choking on a breath that threatened to become something else. He had done this to himself dozens of times before, yeah, but it was _so_ much different when someone else was touching him— when Papyrus was touching him, when he seemed to know exactly how and where to touch- tracing the vertebrae of his spine, the inside of his ribs, fingers getting lower and lower- like he had done it a thousand times, his too-intense gaze burning into him with each movement.

sans opened his mouth to ask what the hell Papyrus had been doing in his free time, but was cut off again when he felt his brother’s teeth make contact with his spine, confidently, like he knew exactly what he wanted to do. The closest thing to a kiss a skeleton could manage, sans thought faintly. And this time, he couldn’t hold back the noise that tore from his throat. Papyrus looked up, _something_ in his expression that made sans squirm, before slowly, slowly, repeating the movement.

“S-shit, pap,” he stuttered, grasping for a hold on the sheets of his bed. Papyrus hummed against him in response, mouth traveling lower, and sans shivered, legs spreading further apart on their own accord as Papyrus reached the hem of his shorts.

He looked up at him in silent askance. sans took a deep breath, and nodded.

He looked away when Papyrus hooked his fingers under the fabric and pulled his shorts down with all the careful reverence of unwrapping his Christmas present from Undyne. sans threw his arm over his eyes.

His brother rubbed small circles into his pelvis, dipped his head and did _something_ interesting with his tongue and where _the hell did papyrus learn to do that holy shit_ and he still couldn’t really get over the fact that this was his _brother_ for god’s sake, this was _Papyrus_ , with one hand reaching up and pressing against that perfect spot on the base of his spine and holy _shit._

“oh _god_ , shit— _papyrus_ ,” he moaned, suddenly breathless.

sans arched off the bed, both hands clutching at the pillow, and he couldn’t really tell what sounds were pouring from his mouth anymore, too focused on the way Papyrus’s fingers dug into his hips and the way his mouth moved against his sacrum and the pleased little hums against his bones.

He came with a broken gasp and a shaky moan, grasping at his pillow like a lifeline.

Papyrus raised his head and _beamed_ , licking his teeth and looking incredibly proud of himself. sans gave a tired smile back.

“You do look _very_ nice like this,” he repeated, as though agreeing with himself. sans felt his face heat up again, and he laughed weakly- he probably looked like a mess. He sure felt like one. His brother had just gotten him off.

“whatever you say, pap,” he shifted uncertainly, “should i, y’know, return the favor?”

“Hm…no, I’m fine,” he said finally, sitting back on his legs. “…Thank you for this, though.”

sans grinned at him, shrugging drowsily, “hey, pap…” he said a few moments later, “did you really think I was having a nightmare earlier?”

Papyrus suddenly looked a bit guilty, grinning apologetically, “No, I… I knew what you were doing.”

…Huh.

sans… really didn’t know what to think about that.

“Anyway,” Papyrus continued, “Do you want anything to eat? I’m sorta hungry after all that.”

sans shook his head, pulling his shorts back up, “i’m sorta _tired_ after all that. it alright if i take a quick nap?”

Papyrus smiled, something small and fond, and nodded, “Lazybones,” he said affectionately, “I’ll wake you up when lunch is ready.”

sans gave a grin in return and shifted onto his side. He heard the door shut softly.

There was silence.

He rubbed at his eye sockets, replaying those last events over in his mind.

That.

Was the single most surreal experience of his life.

 

 


End file.
